A bandgap reference circuit is an indispensable circuit for a mixed signal integrated circuit (IC) for generating a constant voltage regardless of power supply variations, temperature changes and circuit loading from a device. Traditionally, the bandgap reference circuit has two stable points, one of which is a zero point and the other of which is a normal operation point. Therefore, in order to prevent the bandgap reference circuit from locking at the zero point, a start-up circuit is typically added. However, the start-up signal generated by the start-up circuit induces a large current spike which may damage the connected circuits and raises a reliability issue. Accordingly, a new bandgap reference circuit with control mechanism is desired to solve the aforementioned problems.